686139 has 4 divisors (see below), whose sum is σ = 914856. Its totient is φ = 457424.

The previous prime is 686131. The next prime is 686141. The reversal of 686139 is 931686.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 686139 - 2³ = 686131 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (686131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 114354 + ... + 114359.

It is an arithmetic number, because the mean of its divisors is an integer number (228714).

2⁶⁸⁶¹³⁹ is an apocalyptic number.

686139 is a deficient number, since it is larger than the sum of its proper divisors (228717).

686139 is a wasteful number, since it uses less digits than its factorization.

686139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228716.

The product of its digits is 7776, while the sum is 33.

The square root of 686139 is about 828.3350771276. The cubic root of 686139 is about 88.2004298599.

The spelling of 686139 in words is "six hundred eighty-six thousand, one hundred thirty-nine".